Arches National Park in Southern Utah has hundreds of stone arches that draw over a million tourists each year. Looking closely at this photo you can see that a softer portion of the rock tower has collapsed and parts of it lay in the hole. Look carefully again and you will see the arch-shaped crack forming above the hole. This part of the rock will also eventually fall and enlarge the arch even more.

I have visited this place a few times and easily stand up in the large opening, but it's a bit spooky knowing that someday the tons of rock above will come down.

Scroll down about five rows below to see a photo taken from under the arch. It is titled 'fallen arch'.